Scientists look to beetles for water management solutions

Researchers from Johns Hopkins and the State University of New York at Binghamton have been examining seawater trapped inside million year old crystals, in order to study how the chemistry of oceans has changed from the Phanerozoic eon (540 million years ago) to the present.

As bodies of seawater evaporate, crystal precipitates form on the floor of the ocean. These crystals are unique in that they contain tiny inclusions, or hollows, where the seawater becomes trapped. Using electron microscopes and other devices to study these minute amounts of water (some of the inclusions are as small as 30 microns in diameter) scientists can analyze the major ions present in the water.

The research, reported in Science, looked at crystals dating back to various time periods, beginning with the Late Precambrian period (just before the Phanerozoic eon). Their results indicated that the seawater chemistry today is much different from that of millions of years ago.

Moreover, it appears that over the millenniums the seawater chemistry has oscillated, corresponding with fluctuation in seafloor spreading and volcanism.

Such drastic fluctuations in the chemistry of the oceans may have adverse effects on the supply of fresh drinking water on earth. Scientists are constantly searching for new ways to bolster the dwindling supply of fresh water, especially in very arid climates where the water supply is already very scarce.

The Namib Desert in southwestern Africa is home to the highest sand dunes in the world. The desert is virtually devoid of life, receiving practically no rainfall, and only a bit of morning fog. Yet, according to Oxford researchers, a certain type of beetle, native to this desert, has not only managed to survive, but thrive under these almost waterless conditions.

Published in the journal nature, the Oxford researchers describe the mechanisms by which these beetles manage to trap the moisture from the early morning fog that would normally be lost to the heat and winds of the harsh desert climate.

Simply stated, the beetles collect the water from the fog using bumps which line the surface of their backs. The bumps, measuring roughly half a millimeter in diameter, are coated with a hydrophilic substance (one that has a high affinity for water) at the peaks. The valleys between the peaks are covered with a wax-like substance that repels water.

When fog passes over the beetle in the early morning, water accumulates in tiny droplets at the peaks of bumps. Once the droplets have grown so large that their mass overcomes the forces holding them at the peaks, they roll down into the valleys.

At the same time, these large droplets are also massive enough that they will not been blown away by the wind. Thus the droplets roll down the beetles' backs straight into their mouths.

The researchers in this study experimented with the fabrication of their own water-trapping device for harsh climates. They found that such a system was, in fact, easy to make and could have many commercial uses, such as water trapping tents that could significantly contribute to the fresh water supply in countries with very little water.

People living in arid conditions often resort to digging wells as a source of fresh water, but this practice quickly exhausts the available ground water supply because the water is being pumped out of the ground much faster than it can seep back down.

The water-vapor trapping methods proposed by this study could provide a valuable, renewable alternative to well digging, and could increase the supply of fresh drinking water where it is needed most.